The invention discloses a device and a method for predicating a fan load index of a wind powder plant, which belong to the technical field of wind power generation. The method for predicating the fan load index of the wind powder plant adopts a control unit and a mathematical model, wherein the control unit comprises a sensor, a data acquisition chip, a central processing unit, an industrial personal computer and a wireless communication module. The predication comprises the following steps of: 1) establishing input amount; 2) forming a training sample set; 3) inputting an input sample data set into a least-square-method support vector machine model; 4) resolving the least-square-method support vector machine model; and 5) inputting the sample data set to obtain a load index of the wind power plant. The device and the method have the advantages that by realizing the fan state monitoring in a predication process and establishing the least-square-method support vector machine model, the prediction on the fan load index has high precision, high accuracy and high efficiency.